$O(α_s v^2)$ correction to pseudoscalar quarkonium decay to two photons
arXiv:1104.1418 · doi:10.1007/JHEP06(2011)097
Abstract
We investigate the $O(α_s v^2)$ correction to the process of pseudoscalar quarkonium decay to two photons in nonrelativistic QCD (NRQCD) factorization framework. The short-distance coefficient associated with the relative-order $v^2$ NRQCD matrix element is determined to next-to-leading order in $α_s$ through the perturbative matching procedure. Some technical subtleties encountered in calculating the ${O(α_s)$ QCD amplitude are thoroughly addressed.
v2, 28 pages, 2 figures and 2 tables, matching the published version; typos corrected, references added, as well as a "Note added in the proof"